9.1

CVE-2021-26077: atlassian atlassian connect spring boot (acsb) Improper Authentication

Modified
AliasesGHSA-2x7v-w2mv-f3rx
Published 09-05-2021Last modified 12-02-2025

Vulnerability summary

CVE-2021-26077 is a critical (CVSS 9.1) Improper Authentication vulnerability in atlassian atlassian connect spring boot (acsb). EPSS estimates a 0.95% chance of exploitation in the next 30 days, higher than 61.3% of scored vulnerabilities. 1 public exploit is recorded.

Priority
Prioritisepublic exploit

Public exploit (reference, Date unknown)

Source freshness unavailable

How is this decided?
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.95%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits1reference

Timeline

  1. 09-05-2021
    PublishedVulnerability first disclosed.
  2. 12-02-2025
    Last modifiedVulnerability information updated.

Description

Broken Authentication in Atlassian Connect Spring Boot (ACSB) in version 1.1.0 before 2.1.3 and from version 2.1.4 before 2.1.5: Atlassian Connect Spring Boot is a Java Spring Boot package for building Atlassian Connect apps. Authentication between Atlassian products and the Atlassian Connect Spring Boot app occurs with a server-to-server JWT or a context JWT. Atlassian Connect Spring Boot versions 1.1.0 before 2.1.3 and versions 2.1.4 before 2.1.5 erroneously accept context JWTs in lifecycle endpoints (such as installation) where only server-to-server JWTs should be accepted, permitting an attacker to send authenticated re-installation events to an app.

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

0.95%

Chance of exploitation in the next 30 days

Percentile

61%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.95% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

1 found
  • referenceUnverified

    Exploit Reference (community.developer.atlassian.com)

    Maturity: unknown

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Atlassian2 products
Com.atlassian.connect1 product
  • atlassian-connect-spring-boot≥ 1.1.0, < 2.1.3 | ≥ 2.1.4, < 2.1.5

2 vendors · 3 products

References

3 links